"a moral call" is correct and can be used in written English.
You can use it to refer to a statement or action that is based on ethical principles and encourages people to do what is morally right. For example, "The mayor made a moral call for residents to stay home and protect their health during the pandemic."
It was a moral call to action, infused with an activist's rage.
That's a moral call, albeit a rather stupid one in my opinion.
That is a moral call, perhaps heroic, but certainly not one required or sanctioned by international law or covenants.
When it canceled "The Reagans," CBS said it was not responding to pressure, but making a "moral call".
The pope's 180-page encyclical on the environment, released on Thursday, is at its core a moral call for action on phasing out the use of fossil fuels.
At the time, the CBS chairman, Leslie Moonves, declared his decision about "The Reagans" a "moral call," because he concluded its portrayal of the Reagans was unfair.
Now Bush "has embraced Trump-bashing as a moral calling," Franklin Foer wrote in Slate.
While some landlords see a business opportunity or even a moral calling in opening their doors to such a vilified population, many residents say the clusters threaten the safety of their children.
He saw it as a moral calling — "the theory of St. John Bosco is, take the kids from the city and help them" — but it was beginning to wear him out, and he thought more and more about retiring, to spend time with his nine-year-old twin boys, who play soccer.
Here we have a moral calling to the other's needs -- some belief that a rising tide lifts all boats -- baked right into the same document that codified the role of sovereignty itself.
He was a committed mentor who took the responsibility of mentoring almost as if were a moral calling.
